The release of the officers' names came a day after Ventura attorney Ron Bamieh, who represents the Ramirez family, said at a news conference that he plans to file a federal civil-rights lawsuit in the case before the end of the year.

Ramirez's mother, Teresa Ramirez, also called on Wednesday for an FBI investigation into her son's death, saying she does not believe the Ventura County District Attorney's Office will be impartial in its investigation.

Laura Eimiller, a spokeswoman for the FBI in Los Angeles, said Wednesday the agency was investigating allegations that civil rights were violated.

The Ventura County Medical Examiner's Office on Monday said Robert Ramirez died of asphyxia from active prone restraint. The office called the death a homicide but added that this determination only means he died "at the hands of another" and does not necessarily imply intent to cause harm or misconduct.

Robert Ramirez also was found to have had an "extremely high level" of methamphetamine in his blood and a much higher level in his stomach. His temperature, taken shortly after his death, was 106 degrees, in the low range of what's considered potentially lethal, said Dr. Ronald O'Halloran, the county's former chief medical examiner who performed the autopsy.

"That makes a case like this hard to evaluate — what actually caused death. He could have died whether or not there was police involvement at all because his methamphetamine level was so high, it could have caused his death at any time," O'Halloran said Tuesday. "It just wouldn't necessarily cause death."

Mike Adair, a commander with Oxnard police, was asked early Thursday evening why the department chose to release the officers' names now.

"We're releasing them now because we received some inquiries from the press," Adair said, adding, "we decided it would be a good idea to release the names."

Ramirez's family alleges police beat and choked him before he died.

An autopsy report released on this week stated Ramirez had bruises on his face and torso. The report does not state how they were caused.

Attorney Alan Wisotsky, who represents Oxnard police, disagrees with the autopsy's finding that the death was a homicide. Wisotsky called Ramirez's death an unfortunate accident.

Bamieh said there have numerous requests for the names of the officers involved.

"It's nice to see they finally released them," he said, adding "there has been a lack of transparency on the part of Oxnard police during this whole process."